TITUSVILLE — The Humane Society of South Brevard has an operating surplus instead of the $33,000 deficit it claims and has left untouched $61,449 in savings its directors had pledged to use to keep open the Melbourne animal shelter, a county audit shows.

The ''preliminary and incomplete'' findings were reported to commissioners Monday and will be considered at their meeting today at 9 a.m. in Melbourne.

Commissioners ordered the audit in November after shelter officials said they would close this month unless the county increased its $22,500 annual funding to make up the deficit.

The society has said its revenue shortage, outdated facilities and animal populations that number 2,000 to 3,000 more than each of the county's two other shelters warrant more money.

However, the audit of the first six months of the 1985-86 fiscal year, which ends in May, reported $77,172.44 in operating income and $71,232.90 in expenses for a budget surplus so far of $5,939.54.

For the 1984-85 fiscal year, the society had $133,308.98 in income and $136,465.68 in expenses for a deficit of $3,156.70.

It also has $61,449.01 in income from a thrift shop and $13,966.12 in private donations that were not included in its financial statements -- contrary to contract stipulations with the county, the audit reported.

Those funds are earmarked for a new building and have not been touched, the audit said. However, the society's board of directors unanimously agreed in September to borrow money from the thrift shop funds to keep open the shelter, if necessary. That decision is in accordance with a 1982 policy by the board to use that money for the shelter in an emergency, the report said.

Society officials have avoided using their savings for the shelter's operations or maintenance because the county owns the facility, county officials said.

''The society's board of directors should, in compliance with its policy decision of May 11, 1982, authorize disbursement of funds from the thrift shop savings account for shelter operations,'' the audit report said. ''In our considered judgment, imminent shelter closure qualifies as an 'emergency.' '' Contacted Monday, society officials would not discuss the audit in detail. However, they dispute some of its findings, maintaining they have a $33,520 operating deficit.

Society vice president Charles Steiner said the real issue is not the deficit but the county's funding, which he said is not enough. ''Suppose we are $5,900 in the black. We're spending $7,900 every month,'' he said. ''It's all a question of semantics. We think we need to take a stand somewhere.''

The society said recent donations will keep open the shelter through January. Meanwhile, county staff recommendations accompanying the audit propose that commissioners agree to some of the funding request.

Pete Wahl, health and social services coordinator, is recommending that the county increase its annual support by $12,500 to make up for the greater number of animals the south Brevard shelter handles.

The Melbourne facility handles about 44 percent of the workload, although each shelter gets the same amount of money from the county.

Wahl also proposes donating the south and north facilities to their respective societies to help resolve the spending issue. The county owns the shelters in Melbourne and Titusville, valued at $76,000 and $42,000, respectively. The Central Brevard Humane Society owns the Cocoa shelter.